The invention relates to a slip control system for a single-track motor vehicle, particularly to a slip control for a motorcycle.
Conventional slip control systems are sufficiently known in the form of antilock brake control systems (ABS) and wheel slip control system (ASR wheel slip control, ASC automatic stability control). By means of antilock systems, a locking of the wheels is prevented during a braking operation, whereas, in the case of a so-called antislip system, the unintended spinning of a driving wheel is avoided during an acceleration operation. Both systems are based on the control (deviation control) of a slip between at least two wheels (wheel speeds) to be compared.
From German Patent document DE 42 44 112 C2, a slip control system in the form of an antilock system for motorcycles is known, in which the tilting angle of the motorcycle during cornering is determined and, if the latter exceeds a predefined value, the antilock control device is caused, via control signals, to limit the braking pressure at the front wheel to a value which is lower than the locking pressure to be expected. As the tilting position increases, the braking pressure is reduced to a continuously lower value. As a result, a locking protection control which dynamically adapts itself to the degree of the reached tilting position is achieved.
Furthermore, from German Patent document DE 102 35 378 A1, a method is known for controlling the brake on a single-track motor vehicle, in the case of which a side tilt is detected by use of a yaw rate sensor and a brake control takes place as a function of the detected side tilt.
The sensors used for determining the tilting positions, which are sufficiently known in the state of the art, will not be discussed in detail in the following.
The present invention provides a slip control system for a single-track motor vehicle, which is improved with respect to the slip control during a side tilt (tilting position) of the vehicle. The invention recognizes that the wheel slip signals of the front and rear wheel in the case of a single-track vehicle, particularly in the tilting position of the vehicle, are distorted due to the different tire geometries of the front-wheel and rear-wheel tires.
According to the invention, a slip control system for a single-track vehicle is provided that includes devices for detecting the wheel revolutions of the front and rear wheel of the motor vehicle, devices for detecting a tilting position angle of the motor vehicle, as well as devices for influencing the driving and/or braking forces acting upon a wheel of the motor vehicle. Devices for storing tire-type-specific data, which correlate with the lateral rolling radius of the tires are also provided. The devices for influencing the driving and/or braking forces acting upon a vehicle wheel are constructed such that the influencing of the driving and/or braking forces takes place as a function of the tire-type-specific data and the detected tilting position angle, and that an error slip is taken into account which occurs in a tilting position only as a result of the different tire geometries of the front and rear wheel.
According to the invention, at least data for a tire pairing (front and rear wheel) are stored in a memory. However, since usually several tire releases exist for a vehicle, preferably a plurality of tire pairings are stored in the data memory. The pairing of tires actually mounted on the vehicle (or the pairing which is most similar to the actually mounted tire pairing with respect to its relevant data) can either be selected or set by an authorized person, or is automatically recognized by the vehicle at the start of the operation and is used as the basis for the control according to the invention. As a result of the stored data, by way of devices for influencing the driving and/or braking forces acting upon one or both wheels of the vehicle (or all wheels of the single-track vehicle), an improved slip control can take place. The slip control is, in particular, improved in that now a more precise determination of limit values for permissible maximal braking pressures (in the antilock system operation) or permissible maximal acceleration values (in the wheel slip control operation) becomes possible.
For example, when a motorcycle is cornering in a tilting position, solely as a result of the different tire geometries of the front and rear wheel, a slip (in the following called “error slip”) will occur which, so far, had not been taken into account in the state of the art. When cornering with a modern motorcycle, for example, such as a Sporttourer (for example, the BMW R 1100 S) with a tilting position or an angle of tilt of, for example, 45° without an engine drive or braking effect, a speed error of approximately 6% should be expected, by which the rear wheel rotates faster than the front wheel. Because of this error slip, limit values to be calculated, for example, a maximally permissible braking pressure or a maximally permissible acceleration (engine torque) for a corresponding tilting position, are distorted.
In the case of a slip control system according to the invention, as a result of taking into account the different tire geometries of the front wheel and the rear wheel, an error slip occurring in this manner is extracted by calculation, so that the calculation of limit values for an acceleration and/or deceleration of the vehicle during this tilting position, which is corrected by this error slip, supplies considerably more precise limit values for the maximally permissible acceleration or deceleration. If this error slip were not taken into account, in a first consideration of the limit, possibly unacceptably high deceleration or acceleration limit values would be determined, which could cause a reduced acceleration stability because of the reduction of the lateral stability and thus a sideslipping of the motorcycle, or, in a second consideration of the limit, the determined uncorrected deceleration or acceleration values would cause a reduced acceleration efficiency.
The devices for storing the tire data, which preferably are constructed as conventional memories, contain type-specific tire data at least with information concerning rolling radii and/or information concerning the type of tire used (by which conclusions can be drawn on the tread rolling radii).
The slip control system according to the invention is preferably used in an antilock system, a wheel slip control system or a control system of a motorcycle which combines these two systems.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.